That sentence that Obi-Wan quoted actually made me think of something else. Even though, yes this baby is the 1st grandchild since it's your BIL's first kid, she might feel a bit slighted that her other 2 aren't considered grandkids cause they're not his biologically. Also, I'm guessing that since you said something about other issues making you feel bothered by her lack of response that there is some tension in your relationship. And your MIL having concerns and wanting to get everything out on the table makes me think that even more. I mean, it just seems weird cause I think when people were suggesting taking her out to lunch they meant more in like a "you must be so stressed with being 6 months pregnant and buying a new house and having 2 kids to take care of too" kind of way rather than a "let's get everything straightened out" cause I'm sure that won't really help her feel more comfortable or relaxed.